1. Field of the Invention
The present invention relates to a semiconductor device which has a super junction structure.
2. Related Art
A vertical type MOS field effect transistor representing a vertical type semiconductor device is employed to, for example, a power conversion or a power control of a motor for a vehicle or household electric appliance. The one having a super junction structure is disclosed in JP-A-11-233759 and JP-A-9-266311. The super junction structure is constituted by a structure in which a first semiconductor region of first conductive type and a second semiconductor region of second conductive type are arrayed alternately on a semiconductor substrate. This structure has a performance that exceeds a limit performance of silicon can be achieved, and is useful for achieving low resistivity in the vertical type semiconductor device.
In the super junction structure, the alternately arrayed structure of the first conductive type semiconductor region and the second conductive type semiconductor region is terminated at a semiconductor region disposed at an end of the semiconductor substrate. Therefore, a structure of an end of the alternately arrayed structure is very important. When no design is provided to that structure, in a situation where an applied voltage is larger than a withstand voltage at a connection between the first conductive type semiconductor region and the second conductive type semiconductor region, a dielectric breakdown may occur at the semiconductor region disposed at the end of the super junction structure. As a result, the performance exceeding the limit performance of silicon cannot be achieved.